Janita Patel, prosecuting for the RSPCA, said the dog was found by a member of the public in the park shortly before 8pm on August 23 last year.

Ms Patel said Cook had been seen walking out of the park with “blood on his hands” and all over his shins and socks.

The court heard Ronnie, who was still breathing despite suffering severe blood loss, was taken to a vets in Northampton for treatment.

They heard Ronnie had a collar around his neck with a phone number and contact was eventually made with Cook’s father-in-law who attended the vets.

The father-in-law was told the cost of treating Ronnie’s wounds was likely to be £2,500 to £3,000 and he made the decision, on his son-in-law’s behalf, to have the dog put down.

Jennifer Millington, the vet who treated Ronnie, said his injuries were the worst she had seen in her 16-year career.

Ms Millington said Ronnie had sustained deep cuts on his ears, nose and his body.

She said Ronnie would have suffered an “extreme amount of pain” due to his wounds.

Cook, of Greenhill Crescent, Daventry, was interviewed by an RSPCA officer and he accepted that he had caused the injuries to the dog.

He said he had taken Ronnie to a woodland area and stabbed him in the head with a knife after he “went for” his newborn baby and then bit him.

Cook said the dog had also fatally injured four puppies from another dog he owned

When asked why he did not take Ronnie to a vets, Cook said “he should have done”.

He said: “I just lost the plot. I regret my actions. I was trying to protect my family.”

District Judge Tim Daber, sentencing, said it was a “horrendous and horrific” attack on the dog.

He said: “You clearly attacked Ronnie with the intent to kill him with the knife.

“Of course I can understand you feeling extremely emotional and concerned about the welfare of your children. But, after the dog snapped at the child, you took the time to go and get the dog’s lead, at no time did common sense kick in.

“You left that dog with dreadful injuries and there is no excuse for that.”

Cook, who pleaded guilty to causing unnecessary suffering to an animal, was sentenced to 12 weeks in prison. He is likely to serve half before being released on licence. He has been given a lifetime ban from owning any animals. He must also pay £80 costs.